Well tool string



Nov. 5,' 1968 C. C. BROWN WELL TOOL STRING Filed July l2, 1967 5 Sheets-Sheet l ATTRNEY Nov. 5, 1968 c. c. BROWN WELL TOOL STRING 5 Sheets-Sheet 2 Filed July l2, 1967 ATTORNEY Nov. 5, 1968 c. c. BROWN 3,409,095

WELL TOOL STRING Filed July 12, 1967 5 Shee'tS-Sheel 5 ATTOR/Vf'y Nov. 5, 1968 c. c. BROWN WELL TOOL STRING 5 Sheets-Sheet 4.r

Filed July l2. 1967 ATTORNEY Nov. 5, 1968 c. c. BROWN 3,409,096

WELL TOOL STRING .filed July 12, 1967 5 sheets-sheet 5 A TTONE/ United States Patent Oiifce 3,409,096 Patented Nov. 5, 1968 3,409,096 WELL TOOL STRING Cicero C. Brown, Brown Oil Tools Inc., P.O. Box 19236, Houston, Tex. 77024 Filed July 12, 1967, Ser. No. 652,817 3 Claims. (Cl. 175-325) ABSTRACT F THE DISCLOSURE Related applications The present invention is an improvement over that disclosed in my prior copending application, Ser. No. 639,451, tiled May 18, 1967, and entitled, Well Tool Apparatus and Method of Operation.

Reference will also be made herein to other prior copending applications disclosing structural elements related to some of those incorporated in the apparatus of the present invention. These other prior applications are Ser. No. 615,023, filed Feb. 8, 1967, entitled, Well Packer Apparatus, and Serial No. 620,807, led Mar. 6, 1967, entitled, Pump Out Drill Bit.

Background of the invention In connection with the drilling of oil and gas wells, it is often necessary to perform various types of operations in the well bore, some of which may lbe termed repair operations, as for sealing up leaks or improperly located perforations. The sealing will ordinarily be performed by introducing cement into the well casing to form a plug therein adapted to seal up the leaks or improperly located perforations. The cement plug must then be drilled out and the casing reperforated at the proper location or other operations performed, as may be necessary in each particular case.

In conventional operations of the type described, it is necessary that a series of runs with drill pipe, tubing, wire line strings be made in order to introduce the successive forms of tools required to perform the several operations which may be involved. Each time a string of pipe carrying well tools is run into and out of a well, a considerable amount of time is involved which can be very expensive, particularly for the operations conducted at great depths, as is often the case. Also, the removal and re-introduction of pipe strings into a Well may cause loss of control so as to result in hazards to the well, such as blowouts, and the like.

For example, in a not uncommon situation where a well casing has been perforated at a location which does not communicate with the producing formation or a desired section thereof, it is necessary, to shut-off these perforations and reperforate at the correct locations. Closing-oit" of the undesired perforations is generally done by packing-off the `well bore at the proper points and placing a body of cement in the well =bore at a location such as to plug the incorrectly located perforations. Very often this is done under pressure to squeeze off the perforations. This operation requires the running of a string of pipe and other equipment, as may be required, for properly placing the cement, and this equipment must then be removed from the Well bore. Thereafter, as soon as the cement has hardened a drilling string carrying a drill bit must be run back into the well to drill out the cement plug to clear the bore hole. This string must then be withdrawn from the well and replaced by a pipe or wire line string carrying a perforating -gun to reperforate the casing at the proper location.. Thereafter a string of tubing or the like, must be run and set as a production string for the well.

Thus, it lwill be seen that several strips, requiring running and withdrawing pipe strings and tools, must be made into and out of the well bore to complete the series of operations outlined above, all of which necessarily require a substantial amount of time which, in conventional deep well drilling operations, is very costly; or, as noted previously, may prove hazardous to the successful completion of the well.

Summary of the invention The present invention is directed to a tool string for use in a well bore by which a plurality of operations, such as those described above, may beV performed in a Well bore, using a single pipe string, herein sometimes termed a primary pipe string, for performing the several operations required without having to withdraw the same from the Well bore.

In accordance with the present invention, the tool string comprises the combination of a pipe string designed to function as a drill string, carrying on its lower end a two-part bit comprising, a main bit having an axial bore aligned with the bore of the pipe string, and a tubular pilot bit removably secured in the bore of the main bit to 'function as a part of the main bit, and upon removal .from the main bit, to clear the bore of the pipe string and main bit for passage of other tools employed for conducting some of the other operations required.

The general assemblage of apparatus described above has been disclosed in the aforementioned copending application, Ser. No. 639,451. The present invention adds additional structural elements thereto for performance of still other operations required in connection with the procedures employed in well repair operations, such as those described above.

The apparatus in accordance with the present invention, includes in addition to the drill pipe string and tw0- part bit, a packer mounted on the pipe string and arranged to be set and released by manipulation of the pipe string yfor use in sealing off above the formations to be plugged and reperforated, and for use in squeezing cement or other fluids into the surrounding formations. The packer also is provided with novel means by which it may be employed as a scraping tool adapted to scrape the wall of the surrounding casing by reciprocation of the tool string, in order to effectively clean the surface of the casing into which Icement is to be introduced, to thereby assure an effective bond between the cement and the casing.

By use of the apparatus in accordance with this invention, various operations may be conducted either 'before or after perforation, for example. More particularly, the well bore 'below the `bit may be closed olf with a cement plug by employing the tool string, rst as a wall scraping device, and thereafter as a cementing string for placing the cement while the complete two-part bit is in place on the lower end of the drill string; and, after the cement has hardened, the drill string, including the bit, may be employed to drill out the cement plug prior to the running of a perforating gun, or some other tool to -be employed for performing some other operation in the well bore. Thereafter, the drill pipe string, with the pilot bit portion removed, may be employed as the production string for the well, the packer carried thereon having `been set to seal olf the well bore between the pipe string and the surrounding casing above the producing section. The

packer may also `be used in the course of the cementng operation where a squeeze procedure is found to be desirable.

This invention includes the apparatus described which may be employed to perform a plurality of operations in the well bore with a single primary pipe string, without withdrawing the same from the well bore during the course of such operations.

Other and more specific objects and advantages of this invention will lbecome more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates the invention.

In the drawing:

FIGS. 1A, 1B, and 1C, together, constitute a longitudinal, cross-sectional view of a tool string comprising the apparatus in accordance with this invention, the apparatus being shown inside a well casing with a packer in unset condition in the casing;

FIGS. 2 and 3 are generally diagrammatic views showing the apparatus at different stages in the operation of plugging with cement a section of a well casing containing undesired perforations opposite an earth formation;

FIGS. 4 to 7, inclusive, are diagrammatic illustrations similar to FIGS. 2 and 3, showing various additional steps in the operations of the tool string; and

FIGS. 8 and 9 are cross-sectional views taken generally along lines 8-8 and 9-9, respectively of FIG. 1B.

Referring now to the drawings, the tool string comprises:

(a) a pipe string S, which is preferably a string of conventional drill pipe;

(b) a packer, designated generally by the letter P, having a central tubular support or mandrel M which is connected into the drill string to form a portion thereof, as -by means of the collar Q;

(c) a tubular extension E threadedly connected to the lower end of mandrel M to form an additional part of the drill pipe string; and

(d) a two-part drill bit, designated generally by the letter B, threadedly connected to the lower end of extension E.

The latter may carry a centralizer S.

Packer P may be of any suitable and generally conventional form. In the exemplary form illustrated, it is substantially identical with that disclosed particularly in FIGS. 9A and 9B of the aforementioned copending application, Ser. No. 615,023, comprising the several assemblies designated therein Iby the letters H', P', A' and R. However, the anchor assembly A of the present packer embodies certain improvements over anchor assembly A of the packer illustrated and described in the aforementioned application and will -be described in greater detail hereinafter. It should be noted, however, that except for the modified anchor assembly, the details of the packer herein illustrated do not form a part of the present invention, and that anchor assembly A is adapted for use with other forms of packer or other well tools, as will appear subsequently.

Bit B is of the two-part, pump out form disclosed in the aforementioned application, Ser. No. 620,807, lbut may also be of the latched form illustrated in aforementioned application Ser. No. 639,451.

In the f-orm illustrated, bit B comprises a main bit B and a pilot bit B. Main bit B' includes a tubular body 10 having an axial bore 11 and carrying radially extending cutter blades 12 terminating at their lower ends in cutter teeth 12a. Pilot bit B" includes a tubular shank 13 coaxially disposed in Ibore 11 and releasably secured therein to the main 'bit by means of shear pins 13a. Shank 13 carries on its lower end a plurality of angularly spaced cutters 14, the upper ends of which are seated in slots 14a to lock the pilot bit against rotation relative to the main bit. The spaces between cutters 14 form fluid passages communicating through the bore of shank 13 and via the bores of the intervening members with the bore of pipe string S. The inner end of shank 13 defines a seat 30 for engagement of a suitable plugging device, such as the lball K (FIG. 5), which may be pumped through the bore of pipe string S for purposes to 'be described hereinafter. Seal packing 31 is disposed about shank 13 for sealing between the latter and the wall of bore 11 of the main bit.

Packer P includes the tubular body 15 slidably mounted about mandrel M, and the annular resilient seal element 16, the upper end of which is secured to body 15 -by the abutment ring 17. The lower end of seal element 16 carries the expander sleeve 18, the lower end of which is formed to provide the downwardly and inwardly tapering expander cone 19.

Anchor assembly A is mounted on mandrel M below expander cone 19 and comprises a tubular slip cage 20 arranged for slidable movement on the mandrel and ,has mounted on its upper end a plurality of upstanding, angularly spaced, pipe-gripping wedges or slips 21 arranged for radial movement outwardly upon engagement by expander cone 19 in response to downward movement of mandrel M and body 15 relative to cage 20.

Slip cage 20 carries a plurality of angularly spaced, generally rectangular wiper blocks 22 biased outwardly -by spring means 23 to frictionally engage the wall of a surrounding well casing C in which the tool string is run. Each of the wiper blocks carries on its outer face a series of vertically spaced, outwardly projecting arcuate teeth 24, the edges of which are disposed to effectively scrape the inner wall surface of the surrounding casing when the tool string is reciprocated in the casing.

As 'best seen in FIGS. 1B, 8 and 9, the wiper blocks are arranged in at least two sets in axially spaced relation on the slip cage, the blocks of one set 'being angularly oriented with respect to the other so that the edges of the teeth 24 of the several blocks will effectively cover the entire circumference of the inner wall of casing C to thereby assure effective 4cleaning of scale or other detritus from the casing wall in response to then reciprocation of the tool string, as will appear subsequently.

A latch means, designated generally by the letter L, is arranged between packer body 15 and mandrel M to initially hold the packer in unset position, and is arranged to be released by means of a releasing sleeve 25 slidably disposed about mandrel M below anchor assembly A. Release of latch L by means of sleeve 25 is effected 'by longitudinal reciprocation transmitted to mandrel M through pipe string S, as fully described in the aforementioned application, Ser. No. 615,023.

Operation of the tool string will now be described with reference particularly to FIGS. 2 to 7, inclusive.

The tool string, assembled as shown in FIGS. 1A, 1B, and 1C, and with packer P and anchor assembly A in the retracted or unset condition, as shown, will be inserted into casing C through the bore of a conventional preventer stack R mounted on the upper end of casing C. Casing C will extend through earth formations F. As illustrated in FIG. 2, casing C will previously have been perforated by the perforations G at an unsuitable location, which it is desired to close otI so that the earth formation may be reperforated at a lower and preferred location.

When the packer has attained a position in the casing substantially opposite formation F, the entire tool string will be operated to perform a series of short reciprocatory movements within a section of casing to cover a length thereof extending well above and below perforations G, so that scraping teeth 24 may be caused to effectively scrape and thoroughly clean the inner surface of this section of casing C. It will be understood that the stroke of these reciprocatory movements will be less t-han that required to bring releasing sleeve 25 into latchreleasing position.

When this operation has been completed, liquid cement D will be introduced through pipe string S and deposited in the section of casing C opposite formation F, as seen in FIG. 2. Conventional cementing procedures will be used, employing displacing uids, and the cement will be discharged through the passages in bit B.

The next stage of operation will usually be the removal of excess cement by reverse circulation of washing uid through openings in the preventer stack to wash the portion of the cement which extends above the desired level in the casing back through the bit passages and bore of pipe string S to the surface.

As soon as washing out of the excess cement has been completed, if it should be found desirable to squeeze the cement through openings G into the existing formations, packer P will be set by appropriate longitudinal movements of the operating pipe string, as described in the aforementioned application, Ser. No. 615,023. With the packer set, fluid pressure may be applied to the body of cement in place opposite formation F sufficient to force the cement through openings G into the related portions of the earth formation.

When the cement has set, packer P will be released, also as described in aforementioned application, Ser. No. 615,023. Pipe string S will now be free to rotate, and will now be operated as a drilling string, causing bit B to drill out the cement plug which has been formed in casing C opposite formation F, as illustrated in FIG. 4, and thereby clear the bore of casing C.

The next step, illustrated in FIG. 5, is to drop ball K through the bore of pipe string S until it engages seat 30 and closes the bore of shank 13 of the pilot bit, Then uid pressure will be applied through pipe string S to break shear pins 13a and expel pilot bit B from bore 11 of the main bit, to thereby clear the bore of the entire tool string for the passage of other tools, as may be required for the next stage in the operation of the tool string.

In the illustrative embodiment, the next steps, illustrated in FIGS. 6 and 7, will involve reperforating formation F at a lower level and employing the tool string as a production string. In performing these steps, preventer stack R wil be replaced by a casing hanger T in which the upper end of pipe string S will be suitably hung by conventional means and the casing hanger will be surmounted by a conventional Christmas tree X including a lubricator E to enable introduction and removal of tools while the well is under pressure.

Packer P will again be set to seal olf the space between pipe string S and casing C above formation F. Then a conventional perforating gun J suspended on cable N will be run through lubricator E and pipe string S to a point at which new perforations are to be made in formation F. The gun will then be fired in the known manner, producing the new perforations G', whereupon the gun will be withdrawn from the well, and the latter brought into production through pipe string S which will now function as the production string.

From the foregoing, it will be evident that the apparatus described enables the performance of a plurality of operations in a well through the medium of a single operating string without requiring the removal of that string from the well bore at any stage of operation.

It will be understood that various changes may be made in the details of the apparatus described, within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A tool string for use in wells comprising in combination:

a drill pipe string,

a two-part drill bit carried by the drill pipe string and including a main bit having an axial bore,

a tubular pilot bit coaxially inserted in said bore,

and

means releasably securing said pilot bit to said main bit,

a seal packer mounted on the drill pipe string above the bit for sealing with a surrounding well casing, said packer including a tubular support forming a part of said drill string, expansible anchor means mounted about said support and operable when actuated to grippingly engage said surrounding well casing, said anchor means including scraper elements disposed thereon to scrapingly engage the entire circumference of the wall of said surrounding casing in response to the reciprocation of said drill pipe string.

2. A tool string for use in Wells comprising in com bination:

a drill pipe string,

a two-part drill bit carried by the drill pipe string and including a main bit having an axial bore,

a tubular pilot bit coaxially inserted in said bore,

and

means releasably securing said pilot bit to said main bit,

a packer mounted on the drill pipe string above the bit for sealing with a surrounding well casing, said packer including a tubular support forming a part of said drill pipe string, expansible seal means and anchor means mounted about said support and actuatable by reciprocative movements of the drill pipe string, said anchor means including a slip cage slidably mounted on said support, a plurality of an-gularly spaced wiper blocks mounted in the slip cage for frictionally engaging the wall of said well casing, and scraper elements carried by said wiper blocks disposed to scrape the entire circumference of the wall of said casing in response to the reciprocation of said drill pipe string.

3. In a tool string according to claim 2, a plurality of pipe-gripping slips mounted on said cage for radial movement relative to said casing, and an expander means mounted on said support for actuating said slips in response to longitudinal movement of said support relative to said cage.

References Cited UNITED STATES PATENTS 2,783,026 2/1957 Reis'tle 175-325 X 2,883,154 4/1959 Daniel 175-1 2,978,046 4/1961 True 175-325 X 3,151,690 10/1964 Grable 175-325 X 3,253,656 5/1966 Brown 166--129 DAVID H. BROWN, Primary Examiner. 

